+1 on the Chromis.. I added 3 last month and my clowns attacked them immediatly. However, after they killed 2 of them, they decided they had enough. I waited a month and they were still leaving the sole survivor alone. So, I added 2 more last week. Thankfully, my clowns must have gotten it out of their system with the originals as the new guys are doing great.
They add nice activity to the tank and are surprisingly bright colored for the cheap price (2 for $7). I may add 2 more